Windows that are hinged on one side of the sash require latch mechanisms at the other to keep them shut. Such mechanisms are generally comprised of an elongated housing containing a bolt that is biased by a spring so that one end extends beyond an end of the housing. That end of the bolt has a biased striking surface that engages one side of a rail in the jamb when the window is almost closed so that further closure forces the bolt back into the housing. When the window is fully closed, the spring forces the bolt outwardly on the other side of the rail to hold it shut. An opening in the housing permits access to the bolt so that the window can be opened by withdrawing it into the housing.
By way of example, such latch mechanisms may be mounted in the outer edges of the top of a top sash member of a window that pivots about an axis through its bottom sash member so that ready access is provided to the outside of the window for cleaning.
When the sash is made of wood, the latch housing may be mounted in a groove that is routed in the tope of the top sash member that extends through the jamb side of the stile on that side and firmly held therein by screws. Firmly mounting a latch mechanism in a hollow sash made of metal or plastic is more difficult. It is customary to form an elongated opening in the top wall of the top sash member that is parallel to that member and that communicates with an opening in the outer wall of the adjacent stile.
In U.S. Pat. No. 5,139,291, a latch mechanism is described that is adapted to be inserted endwise through the opening in the stile and slid along the elongated opening in the top sash member. The edges of the elongated opening serve as rails that slide into grooves formed between a top plate of the housing and ridges along the outsides of walls depending from the top plate. Special notches are required in the sides of the opening in the stile to permit the ridges to pass. The housing is rigid because of a bottom between the edges of the depending walls so as to form a rectilinear opening in which a spring biased bolt slides. A projection from the bottom engages the inside of the stile when the mechanism is installed so as to prevent it from being forced out of the opening in the stile through which it was inserted. Unfortunately, however, there must be play between the rails formed by the edges of the elongated opening in the top of the sash and the grooves in the sides of the housing to permit the housing to be installed as describe so that a firm mounting is not attached. Furthermore, there must be sufficient play to accommodate variation in the dimensions of the elongated opening.
Another latch mechanism that is produced by Ro-Mai Industries of Twinsburg, Ohio is installed by forcing its housing perpendicularly through the elongated opening in the top of the sash. The edges of the elongated opening fit between the top plate of the housing and rigid tabs on its side walls. In order to accommodate top sash walls of different thicknesses and variations in the dimensions of the elongated opening, fairly wide tolerances must be used so that the latch mechanism is not firmly mounted in all cases.
Furthermore, both the Ro-Mai latch mechanism and that of the patent are difficult to assemble so that the spring and bolt are properly positioned because their housings are four sided and rigid.
A latch mechanism is constructed in accordance with this invention is easy to assemble and can accommodate variations in the thickness of the material from which the sash is made as well as variations in the sizes of the elongated opening in the top of the sash in which they are inserted. Furthermore, special notches are not required in the opening of the stile.
A latch mechanism constructed in accordance with this invention snaps firmly into position when forced perpendicularly through an elongated opening in the top of a top sash that communicates with an opening in the adjacent stile. Its housing is comprised of a top plate that is larger than the elongated opening and a wall having spaced parallel sides and an end depending from the top plate and spaced from its periphery. Resilient tabs extending outwardly from the wall are pushed inwardly as the housing is forced through the elongated opening and snap outwardly when a portion of their tops is below the edge of the opening. The housing is held firmly in position in spite of reasonable variations in the thickness of the edge of the elongated opening and in spite of reasonable variations in its dimensions. Slots that are parallel to the top plate are formed in the sides of the wall.
A bolt of a latch mechanism constructed in accordance with this invention is an elongated member having a base and resilient walls depending therefrom that is adapted to slide between the depending walls of the housing described above with its base adjacent said top plate. The bolt is supported in the housing by wings extending outwardly from the respective resilient walls that are adapted to respectively pass through the slots in the depending walls of the housing. The lower surfaces of the wings slope away from the base so as to draw the walls of the housing toward each other if the base is forced away from the top plate, thus aiding in preventing the bolt from being lost in the hollow sash.
A spring is mounted between the closed end of the housing and the nearer end of the bolt. In the preferred construction, a post extends from the end of the bolt facing the closed end of the housing, and one end of a coiled spring is placed over the post. The other end of the spring bears against the closed end of the housing, and in order to prevent this end of the spring from falling out, the inside of the closed end of the housing is tapered or cup shaped.
In order to aid in accommodating wide tolerances in the thickness of the walls of a sash and in the dimensions of the elongated opening through which the mechanism is inserted, ridges are formed in the tops of the resilient tabs that are perpendicular to the side walls. The ridges make it possible for the tabs to snap outwardly even through the ridges are not entirely below the edges of the elongated opening because it can deform the ridges.